Lens-blank.



L: WILHELM. LENSBLANK.

APPLIOATION FILED FEB. 18, 1908.

901575, Patented 001;. 20, 1908.

H s 2- A ATTEJFQNEY.

UNITED sTA ns PATENT o FIoE.

LOUIS WILHELM, OF WORCESTER, MASSACHUSETTS, ASSIGN'UKUF'O'NE-HALF TO FREDERICK A. STEVENS, OF PROVIDENCE, .RHODE' ISLAND.

LENS-BEANK.

My invention rgates to blanks for bi-focal lenses, which blanks are used by .opticians as the base to which is fused a small auxiliary blank or segment having a different refractive index from that ofthe blank proper to which it is welded to complete the lens.

Heretofore the blanks'made for use in the construction of bi-focal lenses have been formed witlrsmooth faces, whether of concave, convex, on other form, having .a seat or concavity ground in some portion of the smooth face. adapted to receive fusible material for the auxiliary focal member. It is essential to "the fusing process that air or gas bubbles should not occur intermediate the auxiliary material; and the blank. To avoidthis the block .tobe fused must have incomplete surface contact'at the inception of the fusing process. The present method of effecting this end is to manually insert a steel piece intermediate'the blank and the fusible block, but this has been unsatisfactory for several reasons; for instance, the, auxiliary piece slips from between the two members or deranges their relative positions because of the smooth inclined surface upon which the steel piece'rests; furthermore, the presence of the steel piece which is .embedded in the parts after the fusing o eration, sometimes occasions fracture 0 the lens parts in being ground therefrom.

The purpose of my invention is to constructgi lens blank which shall. overcome the above eniunerated defects; and consists es-.

sentially in piawiding an immovable homogeneous supporting means upon the blank, and ml acent the seat of the auxiha'ry focal member.

In, thetdrawings which form a part of this specification, Fu ure 1 1s a lan view of'my, novel blank. Flg. 2, a section of the Specification of Letters Patent.

Application filed February 18,1908. Serial No. 416,621.

, cave, or plano-convex.

ing'parts of the disk and Patented Oct. so, 1908.

same on line :0 w'of Fig. 1, showing in section an auxiliary blank positioned prepar-.

atory to fusing. Figs. 3 and 4 are similar sections respectively of the same parts during the subsequent steps of manufacture of a i-focal lens. Figs. 5 and 6, plan views of modified forms of my blank, and Fig. 7, a section on line y 3 of Fig. 6 showing in broken outlinethe auxiliary fusible member.

Likereference characters indicate like parts throughout the views. Y

My novel blank comprises a lens body, A, which in general outline may be of any usual contour,.such as concave, convex, plano-con- In this instance, the body is plane-convex in form; a, indicating the convex surface. The body is formed by molding. The molds are provided with cavities and a convex projection, with the rerelation to each other, and the cavlty is within and concentric with the projections. The projections." fare j elljacent and equidistant from theymarginof the cavity, C. The surface of the cavity,,-C, may be later ground.

The projections in" this instance are vertical and rounded,'but thisparticular shape is not of the projections, B, are cut away to form tions, B are ar'cuate in form.

In Figs. 2, 3 and 4 are shown they manner in which my novel lens blank maybe utilized by optioians. "The operator places a disk, D, of easily fusible glass, havin a different refractive index from that othe blank, A, upon theprojection or projections, B. Un-

der heat, the disk sinks into the cavity, C, as shown in Fig. 3, and is fused and welded with the blank. After cooling, the project-- ground off and the whole polished.

What I claim is, 1. In a lens blank, the combination with the body, of integral projections upon the face of the bod 2. In a lens blank, the combination with rojections are "essential; "In Figs. 6 and 7 the inner sides the body of circularly disposed integral pro- 1 integral p10jections circularly disposed upon jections upon the face of the body. the iace'of the body around the cavity. 10 3. Inn lens blank, the combination with In testimony whereof I have aflixed my the body provided with a concave cavity, I signature in presence of two witnesses.

of integral projections upon the face of the l LOUIS \VILHE LM.

4. In a lens blank, the combination with HORATIO E. BELLOWS,

body adjacent the margin of the cavity. Witnesses: the body, provided with a concave cavity, of JOSEPH E. BURNS. 

